The Trump administration demanded in unusually strong terms Friday that Kurdish leaders in Iraq cancel a referendum on independence set for later this month, saying it was “distracting” from the military effort against Islamic State terrorists.

The White House statement came hours after the parliament of Iraqi Kurdistan voted to go ahead with the referendum. The developments are the latest in an intensifying campaign, some of it waged on Capitol Hill, over whether the Kurds should hold the vote. It’s an especially sensitive issue because the Kurds are critical U.S. allies in the anti-terrorism fight in Iraq and Syria, providing ground troops that have scored numerous successes.

“The United States does not support the Kurdistan Regional Government’s intention to hold a referendum later this month,” White House press secretary Sarah Huckabee Sanders said Friday. “The United States has repeatedly emphasized to the leaders of the Kurdistan Regional Government that the referendum is distracting from efforts to defeat [the Islamic State] and stabilize the liberated areas.”